Electroerosion of metal parts is generally well known. There are two different basic types of machines for electroerosion. In one of the types of machine, a wire electrode is placed with one end adjacent to a workpiece. The wire electrode is used up in the process of electroerosion. Machines of this type are shown in a number of U.S. Letters Patents, and typical are: U.S. Letters Pat. No. 3,604,883 to Dietz entitled MULTIPLE ELECTRODE ASSEMBLY FOR ELECTRICAL DISCHARGE MACHINING; U.S. Letters Pat. No. 4,041,269 to Baker for CARTRIDGE FOR AN ELECTRICAL DISCHARGE MACHINING APPARATUS, and U.S. Letters Pat. No. 4,044,216 to Check el at for MULTIPLE ELECTRODE ELECTRICAL DISCHARGE MACHINING. Each of the foregoing disclosures teaches multiple wire electrodes.
On the other hand, the other type of machine has a continuous wire which moves pass the workpiece during the electroerosion, and the wire is not used up, but rather is collected.
Typical disclosures of various machines which have a moving continuous wire are contained in: U.S. Letters Pat. No. 3,822,374 to Ullmann, et al entitled ELECTRODE WIRE FEED MECHANISM FOR ELECTRO-EROSION MACHINES; U.S. Letters Pat. No. 3,849,624 to Dulebohn, et al entitled WIRE ELECTRODE ELECTRIC EROSION DEVICE; U.S. Letters Pat. No. 3,946,189 to Pomella, et al entitled ELECTROEROSION APPARATUS HAVING A CYCLICALLY MOVABLE AND VARIABLY INCLINED WIRE ELECTRODE; U.S. Letters Pat. No. 3,987,270 to Ulmann, et al entitled AUTOMATIC SET-UP ELECTROEROSION MACHINING METHOD AND APPARATUS; U.S. Letters Pat. No. 4,002,885 to Bell, Jr., et al entitled SERVO FEED SYSTEM FOR A WIRE ELECTRODE TYPE ELECTRICAL DISCHARGE MACHINING APPARATUS; U.S. Letters Pat. No. 4,016,395 to Rietveld entitled WIRE ELECTRODE FEED SYSTEM FOR ELECTRICAL DISCHARGE MACHINING; U.S. Letters Pat. No. 4,029,929 to Rietveld entitled ELECTRICAL DISCHARGE MACHINING DEVICE FOR CUTTING WITH WIRE ELECTRODE; U.S. Letters Pat. No. 4,052,583 to Inoue entitled METHOD OF AND APPARATUS FOR ELECTRICAL DISCHARGE MACHINING WITH A TRAVELING-WIRE ELECTRODE and U.S. Letters Pat. No. 4,084,074 to Gilleland, et al entitled WIRE ELECTRODE PROTECTION SYSTEM FOR ELECTRICAL DISCHARGE MACHINING. This second group of patents which relate to non-destruction of wire electrode electroerosion machines do not disclose any multiple wire electroerosion machines.
Although the use of multiple wire electrodes is well known in the art for use in electrodes, wherein the electrodes are consumed, the use of multiple electrodes has not been heretofore successfully used in systems, wherein the wire moves past the workpiece and is not consumed.
It has been found that the utilization of multiple electrodes in the non-consuming systems has been most difficult. Some of the problems which have been encountered is that the wire of one or more of the cutting wires break, or the cutting is erratic, that is, the cut is not true.
It is desirable to make multiple cuts with a single electroerosion machine to reduce the machining time of like parts.